Mooring systems are known in the prior art. In WO 97/29943 a mooring system is described which includes a bridle having a star-like shape that is useful for mooring a single vessel or for mooring two or more vessels relative to one another. The mooring system describes in WO 97/29943 has a mooring bridle formed of a plurality of anchor connections spaced about a central mooring position. The system includes connecting lines attached to non-adjacent anchor buoys and attachable to the additional vessel and includes mooring lines attachable to the additional vessel holding the vessel to the mooring bridle. The mooring lines each include an anchor (of the adjacent anchor connection), an anchor line, an anchor buoy, and a vessel line. In an alternative the system described in WO 97/29943 includes interconnecting two mooring bridles to provide for close, effective mooring of two vessels relative to one another.
U.S. Pat. No. 4,342,277 illustrates a system for anchoring a large number of interconnected mooring floats in either deep or shallow bodies of water. The system includes a grid of post-tensioned cables positioned beneath the floats and a number of anchoring lines extending between the grid and attachment fixtures forming part of the floats.
U.S. Pat. No. 5,704,307 illustrates a taut leg bow mooring system which includes an anchor positioned on the floor of the sea. A riser line is secured to and extends upwardly from the anchor, and a submerged buoy secured to the end of the riser line from the anchor.
It is limitation of all the above mentioned prior art solutions that even though a vessel may be connected to the mooring system in a removable fashion, all of the mooring structures rely on elements extending up to the surface of the sea, permanently situated at or near the surface of the sea when the mooring system has been positioned.
In the mooring system of WO 97/29943 the platform forms an integral part of the mooring grid, meaning that the mooring grid will at least partly collapse and alter shape and positions of many of its structural elements if the platform is removed. Hence this mooring grid does not allow for the removal of all surface components without loosing its form. On the one hand, system elements remaining on the surface may form an undesirable obstruction. On the other hand in a system where the surface elements are also removed, the mooring system changes shape and position, thereby making it difficult to restore to its desired operation.
The anchoring system for floating moorage disclosed in U.S. Pat. No. 4,342,277 needs several floats at the surface of the sea to remain intact. If these surface floats were removed the anchoring system would fall to the bottom of the sea and be very hard to reinstall into its original shape.
There is thus a need for a more flexible mooring system which improves the predictability of the mooring of surface vessels or the like, and which provides reduced a hindrance or restriction when there are no surface vessels or the like coupled to the mooring system.
Preferably, such a mooring system should enable the mooring of a number of platforms or vessels in at all depths in such a way that the mooring is able to withstand the forces typically occurring within such systems in such waters.
In some cases a mooring system should enable the mooring in shallow to deep waters of multiple platforms or vessels in substantially fixed positions relative to each other without resulting in excessive straining forces in any part of the system.
It is thus an object of the invention to provide a mooring system which allows improved freedom of movement for surface platforms or vessels while at the same time having a possibility of secure mooring of a vessel or platform at some location at or near a mooring point while taking into account variation in ocean floor shapes and depths.